/*
 * Copyright (C) 2022 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "CSSToLengthConversionData.h"
#include "CSSValue.h"
#include "CSSValueKeywords.h"
#include <wtf/CheckedPtr.h>
#include <wtf/OptionSet.h>
#include <wtf/text/AtomString.h>

namespace WebCore {

class RenderElement;

namespace MQ {

enum class LogicalOperator : uint8_t { And, Or, Not };
enum class ComparisonOperator : uint8_t { LessThan, LessThanOrEqual, Equal, GreaterThan, GreaterThanOrEqual };
enum class Syntax : uint8_t { Boolean, Plain, Range };

struct Condition;
struct FeatureSchema;

struct Comparison {
    ComparisonOperator op;
    RefPtr<CSSValue> value;
};

struct Feature {
    AtomString name;
    Syntax syntax;
    std::optional<Comparison> leftComparison;
    std::optional<Comparison> rightComparison;

    const FeatureSchema* schema { nullptr };
};

struct GeneralEnclosed {
    String name;
    String text;
};

using QueryInParens = std::variant<Condition, Feature, GeneralEnclosed>;

struct Condition {
    LogicalOperator logicalOperator { LogicalOperator::And };
    Vector<QueryInParens> queries;
};

enum class EvaluationResult : uint8_t { False, True, Unknown };

struct FeatureEvaluationContext {
    CheckedRef<const Document> document;
    CSSToLengthConversionData conversionData { };
    CheckedPtr<const RenderElement> renderer { };
};

struct FeatureSchema {
    WTF_MAKE_STRUCT_FAST_ALLOCATED;

    enum class Type : uint8_t { Discrete, Range };
    enum class ValueType : uint8_t { Integer, Number, Length, Ratio, Resolution, Identifier };

    AtomString name;
    Type type;
    ValueType valueType;
    FixedVector<CSSValueID> valueIdentifiers;

    virtual EvaluationResult evaluate(const Feature&, const FeatureEvaluationContext&) const { return EvaluationResult::Unknown; }

    FeatureSchema(const AtomString& name, Type type, ValueType valueType, FixedVector<CSSValueID>&& valueIdentifiers = { })
        : name(name)
        , type(type)
        , valueType(valueType)
        , valueIdentifiers(WTFMove(valueIdentifiers))
    { }
    virtual ~FeatureSchema() = default;
};

template<typename TraverseFunction> void traverseFeatures(const Condition&, TraverseFunction&&);

template<typename TraverseFunction>
void traverseFeatures(const QueryInParens& queryInParens, TraverseFunction&& function)
{
    return WTF::switchOn(queryInParens, [&](const Condition& condition) {
        traverseFeatures(condition, function);
    }, [&](const MQ::Feature& feature) {
        function(feature);
    }, [&](const MQ::GeneralEnclosed&) {
        return;
    });
}

template<typename TraverseFunction>
void traverseFeatures(const Condition& condition, TraverseFunction&& function)
{
    for (auto& queryInParens : condition.queries)
        traverseFeatures(queryInParens, function);
}


}
}
